Order Thalassiosirales

Family Lauderiaceae (Schütt) Lemmermann

Genus Bacterosira Gran

• Bactеrosira bathyomphala (Cleve) E. E. Sylversten & G. R. Hasle – marine; planktonic; dominant; typical in late spring (Конопля, 1974: as B. fragilis Gran; marine; planktonic (Сёмина, Сергеева, 1983: as B. fragilis).

Genus Lauderia Cleve

• Lauderia annulata Cleve – marine; planktonic; typical in late spring; dominant in autumn (Конопля, 1974: as Lauderia borealis Gran)

Family Skeletonematacae Lebour

Genus Detonula Schütt

• Detonula confervacea (Cleve) Gran – marine; planktonic (Конопля, 1974; Rat'kova, 2000).

Genus Skeletonema Greville

• Skeletonema costatum (Greville) Cleve – marine; planktonic; dominant (Конопля, 1971). Marine; planktonic; typical in summer, dominant in July (Конопля, 1974). Marine; planktonic (Сёмина, Сергеева, 1983).

Family Stephanodiscaceae Glezer & Makarova

Genus Cyclostephanos Round

• Cyclostephanos dubius (Fricke) Round in Theriot et al. – freshwater; periphyton (Dressler, 2003).

Genus Cyclotella (Kützing) Brébisson, 1838

• Cyclotella antiqua W. Smith – freshwater; periphyton (Dressler, 2003).
• Cyclotella choctawhatcheeana Prasad, 1990 - marine, plankton. Found in semi-isolated coastal stratified lake Kislo-Sladkoe, at the depth of 0 to 2–2.5 m (Mindolina et al., 2023).
• Cyclotella comensis Grunow – freshwater; periphyton (Dressler, 2003).
• Cyclotella comta (Ehrenberg) Kützing – marine, littoral; diluted areas; rare (Бондарчук, 1970). Marine, area near the mouth of the Nilma river; planktonic; dominant (Лихачёва, 2003).
• Cyclotella kuetzingiana Thwaites – marine, littoral; diluted areas; rare (Бондарчук, 1970).
• Cyclotella litoralis Lange & Syvertsen — marine, planktonic (Rat'kova, 2000).
• Cyclotella meneghiniana Kützing – marine, littoral; benthic, periphyton; sporadic (Бондарчук, 1970). Marine, area near the mouth of the Nilma river; planktonic; dominant (Лихачёва, 2003). Freshwater; periphyton (Dressler, 2003). Laso in semi-isolated coastal stratified lake Kislo-Sladkoe, at a depth of 0 to 2–2.5 m (Mindolina et al., 2023).
• Cyclotella cf. michiganiana Skvortzov – freshwater; periphyton (Dressler, 2003).
• Cyclotella ocellata Pantocsek – freshwater; periphyton (Dressler, 2003).
• Cyclotella operculata (C. Agardh) Kützing – marine, littoral; sporadic (Бондарчук, 1970).
• Cyclotella radiosa (Grunow) Lemmermann – freshwater; periphyton (Dressler, 2003).
• Cyclotella rossii Håkansson – freshwater; periphyton (Dressler, 2003).
• Cyclotella stelligera Cleve & Grunow – marine, littoral; diluted areas; sporadic (Бондарчук, 1970). Freshwater; periphyton (Dressler, 2003).
• Cyclotella striata (Kützing) Grunow — marine, planktonic (Rat'kova, 2000); planktonic, sporadic, Verkhneye (Upper) Lake.

Genus Stephanodiscus Ehrenberg

• Stephanodiscus astraea (Kützing) Grunow – marine, littoral; diluted areas; rare (Бондарчук, 1970).
• Stephanodiscus minutulus (Kützing) Cleve & Möller – marine, littoral; diluted areas (Бондарчук, 1970: S. astraea var. minutula (Kützing) Grunow).
• Stephanodiscus neoastraea Håkansson & Hickel – freshwater; periphyton (Dressler, 2003).

Family 'Thalassiosiraceae

Genus Porosira Jørgensen

• Porosira glacialis (Grunow) Jørgensen – marine; planktonic (Конопля, 1974).

Genus Thalassiosira Cleve

• Thalassiosira angulata (Gregory) Hasle (=Th. decipiens (Grunow) E. G. Jørgensen) – marine, littoral; sporadic (Бондарчук, 1970). Marine; planktonic (Конопля, 1974).
• Thalassiosira anguste-lineata (A. Schmidt) G. Fryxell & Hasle (=Coscinosira polychorda (Gran) Gran) – marine, littoral; sporadic (Бондарчук, 1970). Marine; planktonic (Конопля, 1974).
• Thalassiosira antarctica Comber (Rat'kova, 2000: as Thalassiosira antarctica var. borealis G. Fryxell et al.).
• Thalassiosira baltica (Grunow) Ostenfeld — planktonic, rare, Rugozerskaya Bay
• Thalassiosira bioculata (Grunow) Ostenfeld – marine; planktonic (Конопля, 1974).
• Thalassiosira bulbosa E. E. Syvertsen — marine, planktonic (Rat'kova, 2000).
• Thalassiosira constricta Gaarder — marine, planktonic (Rat'kova, 2000).
• Thalassiosira excentrica (Ehrenberg) Cleve – marine; planktonic (Конопля, 1974).
• Thalassiosira gravida Cleve – marine, littoral; benthic, periphyton; sporadic (Бондарчук, 1970). Marine; planktonic; dominant in spring (Конопля, 1971). Marine; planktonic; dominant (Конопля, 1974). Marine; planktonic (Сёмина, Сергеева, 1983).
• Thalassiosira hyalina (Grunow) Gran – marine; planktonic (Конопля, 1974).
• Thalassiosira hyperborea (Grunow) Hasle & Lange — marine, planktonic (Rat'kova, 2000).
• Thalassiosira kushirensis — marine, planktonic (Rat'kova, 2000).
• Thalassiosira leptopus (Grunow ex Van Heurck) Hasle & G. Fryxell – marine, littoral; benthic, periphyton; sporadic (Бондарчук, 1970: as Coscinodiscus lineatus Ehrenberg).
• Thalassiosira cf. lineoides Herzig & Fryxell — marine, planktonic (Rat'kova, 2000).
• Thalassiosira nordenskioeldii Cleve – marine, littoral; sporadic, everywhere (Бондарчук, 1970). Marine; planktonic (Конопля, 1974; Сёмина, Сергеева, 1983).

rus: Порядок Thalassiosirales